/Engine/Source/Runtime/Engine/Classes/GameFramework/GameUserSettings.h
Request a change to the specified resolution and window mode. Optionally apply cmd line overrides.
static void RequestResolutionChange ( int32 InResolutionX, int32 InResolutionY, [EWindowMode::Type](API\Runtime\ApplicationCore\GenericPlatform\EWindowMode__Type) InWindowMode, bool bInDoOverrides )